Air conditioning unit



ec. 7, 1937. v w c w 2,101,467

AIR CONDITIONING UNIT Filed March 21, 1955 2 Sheets-Sheet 1 1 ec. 7, 1937. T. w. CARRAWAY 2,101,467

. AIR CONDITIONING UNIT Filed March 21, 1935 2 Sheets-Sheet 2 Patented Dec. 7, 1937 UNITED STATES PATENT OFFICE AIR CONDITIONING UNIT Application March 21 1935, Serial No. 12,153

7 Claims.

This invention relates to new and useful improvements in air conditioning units.

One object of the invention is to provide an improved air conditioning unit which will efficiently lower the temperature of the air passing therethrough, as well as extract moisture therefrom in a single operation.

An important object of the invention is to provide an improved cooling unit including a plurality of coils, through which refrigerant is circulated, the coils being individually and automatically controlled according to the loads imposed thereon, whereby a balance may be obtained between the coils to extract a certain amount of moisture without lowering the temperature below a desired degree, thereby eliminating the necessity for re-heating the air after the moisture has been extracted and before discharging it into the area to be conditioned.

Another object of the invention is to provide a plurality of coils through which refrigerant is circulated. each coil having a thermostatic valve for controlling the refrigerant flowing therethrough and each valve being controlled by a thermosensitive element connected with, and actuated by, the discharge line of its coil, wherein such valve is connected, whereby the heat of the outgoing refrigerant controls the flow through the valve, which results in the valve being controlled by the load imposed on its coil.

A further object of the invention is to provide a cooling unit which is operated at its highest rated efllciency under normal conditions, but which will be forced, to take care of abnormal conditions, the control being automatic and governed by the temperature of the air outside the area to be conditioned.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings in which an example of the invention is shown, and

wherein:

Figure 1 is a view partly in elevation and partly in section of a conditioning unit constructed in' Figure 5 is an isometric view of a portion of the cooling coils together with the supporting fins.

In the drawings, the numeral I0 designates a vertical casing which may be constructed of sheet metal, or other suitable material, and is pref-' erably provided with insulated walls II. An air v impeller or blower l2, having an air intake flue I3 is mounted within the lower end of the cabinet. The flue I3 is connected with the outside of the room or area to be conditioned, whereby fresh air is supplied to the blower. A discharge fiue l4 extends from the top of the casing l0 and this flue has its other end (not shown) leading into the area to be conditioned, and it is obvious that air discharged from the casing will be introduced into the conditioned area.

In the cooling of air it is necessary, in order to obtain maximum comfort in the conditioned area, to remove a certain amount of moisture from the outside air as well as to lower the temperature thereof. In other words to properly condition the air, latent heat, as well as sensible heat, must be removed from said air. Heretofore, it has been a problem to extract the exact amount of moisture while lowering the temperature of the air to such a degree that the desired amount of moisture is extracted. This method necessitates lowering the temperature to such an extent that it should not be delivered into the conditioned area in this condition, so it has been the customary practice to heat the air after it has passed through the cooling medium to raise the temperature in order that maximum comfort in the conditioned area is had. This requires two complete operations and necessitates the use of a heater in combination with the cooling unit, which adds much to the operating expense. Also it is diflicult to operate the heater accurately to obtain the correct temperature becausev of the variation of the temperature of the incoming air.

In some cases,- the heater has been eliminated and outside air introduced into the cooled air, which has had a. proper amount of moisture removed therefrom. This outside air, being of a higher temperature serves to raise the temperature of the cooled air, so that comfort may be maintained in the conditioned area. However, this method requiresintricate control and expensive apparatus.

' The cooling unit l5 shown in the drawings lowers the temperature a desired degree and removes a certain amount of-moisture in a single. operation, whereby the air passing to the conditioned area is such as will make for maximum comfort. The cooling unit as shown includes two individual coils i6 and I! which are disposed one above the other and are supported in fins i8 which extend transversely across the interior of the casing above the blower. The coils are preferably located in staggered relation, as clearly shown in Figures 1, 2, 4 and 5, whereby they substantially cover the entire interior area of said casing. In this connection, it is to be understood that, obviously, while two separate coils i6 and IT, as shown, are sufficient for some installations, a greater number of coils may be employed in other installations.

The lower coil 16 has an inlet pipe I9 connected at one end thereto with its other end connected to a reservoir or tank 20 of a condensing unit 2|. The upper coil has a similar inlet pipe 22 conmeeting said coil with the tank 20. Outlet pipes 23 and 24 lead from the other ends of the lower and upper coils, respectively, and are connected with the compressor 25 of the unit. An electric motor 26, or other suitable means, is provided for operating the compressor.

A refrigerant, such as freon, is introduced into the coils and it is obvious that said refrigerant is circulated from the tank 20 through the coils and then back. to the compressor 25. compressor, the refrigerant is conducted to condensing coils 21, where the heat is extracted, and then back to the tank 20. Thus, it will be seen that a constant circulation of the refrigerant through the coils is had. It is pointed out that the various parts of the condensing unit 2| are subject to variation. In this connection, it is noted that the refrigerant is maintained at the same temperature in the several coils of the cooling unit l5, it being supplied from one and same source 20.

When the condensing unit is operating, the liquid refrigerant which is under pressure flows from the tank through the pipes l9 and 22 to'the coils. The pipe I9 is provided with a thermostatic expansion valve 30, while the pipe 22 is provided with a similar valve 3|, said valves being positioned as shown in Figure 1, so that just before the refrigerant enters the coils, the pressure of said refrigerant is reduced due to the sudden expansion. As the air within the casing is from the air. The refrigerant, which is heatedby the heat exchange occurring through contact with the warm air, then flows through the outlet pipes 23 and 24 to the compressor 25,as has just been explained. The operation of the valves 30 and 3| is entirely automatic, being actuated by the load imposed on the coils. The thermostatic valve 30 controlling the refrigerant flowing to the coil I6 is connected by a capillary tube 32 with a thermostatic bulb 33. The bulb is secured to the outlet pipe 23 of the coil 16. When the gas within the bulb becomes heate'd, it will open the valve 30. When the gas cools, it will close said ,valve. Therefore, it is-obvious that the operation of said valve is directly controlled by the heat of the refrigerant which is leaving the coil L6 through the outlet pipe 23. Since the temperature resulting from theheat of the refrigerant depends on the load imposed on the coil, that is, the temperature and humidity of the air striking the coil, it will be seen that the valve is controlled by the load imposed on the coil. The refrigerant in the upper coil 11 is From the controlled in a similar way, the valve 3| being connected with a thermostatic bulb 34 by a capillary tube 35, whereby the temperature of the outgoing refrigerant controls the valve, thereby controlling the refrigerant entering the upper coil. It is pointed out that each coil is independent of the other, there being no connection therebetween. Each coil individually controls its valve automatically to regulate the incoming refrigerant.

In operation, assuming the normal or average temperature where the unit is installed to be degrees, the coils and condensing unit are constructed to operate at their highest rated efficiency to extract the desired amount of moisture and to lower the temperature to a desired degree. Therefore, if the temperature of the refrigerant is 40 degrees, under normal operating conditions, then when air of a temperature of 85 degrees, which is above the dewpoint, normally strikes the coil, the refrigerant first extracts sensible heat to lower the temperature before extracting any latent heat. For purposes of illustration, assuming it isdesired to extract 7 grains of moisture and to lower the temperature 10 degrees, or in other words, to 75 degrees, the maximum capacity of the lower coil when its valve 30 is open, is only sufficient to extract 5 grains of moisture, and lower the temperature 6 degrees. Then the upper coil need only extract 2 grains of moisture and further lower the temperature 4 degrees. In other words, it'is unnecessary to operate one, or both coils, at a maximum capacity at all times because of the variation, not only in the temperature of the air, but also in the moisture content.

The valves 30 and 3| control the coils according to the varying loads.

Air, at a temperature of 85 degrees, discharging against the lower coil will cause a rapid heating of the refrigerant in this coil. The heat of the refrigerant acts upon the thermostatic bulb 33 to move the valve 30 to a wide open position, whereby the coil is operating to handle its maximum capacity. So long as the temperature of the air, as well as the moisture content thereof, remains the same, the valve remains open.

Since the lower coil l6 removes a certain amount of moisture and lowers the temperature of the air to a certain degree, it is obvious that the air striking the upper coil is at a different temperature than it was upon contacting the lower coil. Therefore, because the temperature of the refrigerant within both coils is the same, the air striking the upper will not. heat the refrigerant within said upper to as high a degree as the refrigerant in the lower coil was heated. Thus, the temperature of the outgoing refrigerant in the uppercoil passing through the outlet pipe 24, which acts upon the bulb 3, will cause said bulb to keep the valve 3| operating with regularity, whereby only sufficient refrigerant to do the necessary work is admitted to the upper coil l1. With this, a balance is obtained between the upper and lower coils, the upper coil completing the conditioning of the air to the desired degree.

Assuming that the temperature of the air striking the lower coil should drop to 75 degrees, then it is obvious it would be unnecessary for the lower coil I to be operated to handle its maximum capacity. Therefore, the refrigerant passing from this coil under this condition would not be heated as much as it would when 85 degree air was passing therethrough. As a result, its inlet valve 3| would be actuated accordingly. The upper coil Il would be similarly controlled by its valve 3|.

Should an extreme condition arise, such as an increased moisture content to be present in air of 85 degrees, then the lower coil would extract only part of the latent heat or moisture. Its capacity would be insuflicient to extract this increased latent heat and lower the temperature sufficiently. Therefore, the upper coil would then come into operation, the valve 3| would be opened and the upper coil would do the remaining work to properly condition the air.

To take care of abnormal conditions, in some cases, the electrical motor 26 of the condensing unit may be provided with two speeds. Under the low speed, maximum efflciency of the coils and condenser is had. But in cases where the outside temperature rises appreciably above normal, the capacity of the coils would be insuflicient to take care of this abnormal condition. In such event, the motor may be automatically operated at the higher speed which speeds up the compressor. This results in a lowering of the temperature of the refrigerant from 40 degrees, if, for example, this be the normal operating temperature, to 32 degrees, whereby the given amount of refrigerant con extract more heat units both sensible and latent. However, when the motor is speeded up, the coils and compressor operate inefficiently, that is, because the coils have been adjusted to handle a normal temperature. Therefore, to condition air of an abnormal temperature, they must be forced, which results in a sacrifice in eificiency. However, this abnormal condition is unusual and very seldom lasts for any length of time. Therefore, the greater percentage of time, the entire unit is operating at its highest rated efliciency.

For automatically speeding up the motor. an outer temperature control 35 is provided. -This control is electrically connected with a two speed typeof motor control 36 for the condensing unit motor 26. The control 35v may obviously comprise a globule of mercury which is actuated by an abnormal temperature change. This globule is arranged to engage either a contact 31 or a contact 38, each of which is electrically connected in one of the motor speed circuits. Under normal outside temperature, the motor operates at a low speed to actuate the condenser at its highest eificiency. Under abnormal conditions, the condenser must be forced to take care of such condition. In either event, the control valves 30 and 3|, which are individually controlled by the loads imposed on their respective coils l6 and H, are operated in the same manner. It is again pointed out that the coils l6 and I I are independent of each other and are not connected in series. So, too, it is again stressed that the provision for op-- erating the motor 26 at different speeds is not made in all installations, because it is preferable to provide coils of the character of the herein described coils l6 and H of a capacity to take care of predetermined maximum degrees of temperature and humidity. I

' What I claim and desire to secure by Letters Patent, is:

1, An air conditioning unit comprising a casing, means' for passing air to be conditioned through said casing, a plurality of separate cooling elements within the casing successively through which the air is passed, the refrigerant being maintained at substantially the same temperature in the several cooling elements, and individual means for independently controlling the supply of refrigerant to each cooling element according to the load imposed on each element.

2. An air conditioning unit comprising, a casing, means for passing air to be conditioned upwardly through said casing, a multiplicity of individual cooling coils disposed horizontally and the one above the other within said casing in the path of the passing air, the refrigerant being maintained at substantially the same temperature in the several cooling coils, individual control means for the supply of refrigerant to each cooling coil separately, and means for automatically operating each individual control means according to the load imposed upon each cooling coil.

3. An air conditioning unit comprising, a cas ing, means for passing air to be conditioned through said casing from outside the area to be air conditioned, a multiplicity of individual cooling elements within the casing in the path of the frigerant return fromeach cooling element in its particular refrigerant circulating system for automatically controlling the admittance of the refrigerating medium individually to each cooling element.

4. An air conditioning unit comprising, 9. casing, means for passing air to be conditioned through said casing from outside the area to be air conditioned, a multiplicity of cooling coils arranged in said casing transversely of the path of the passing air, the respective coils being arranged in staggered relation to each other but spaced apart for the passage of the air therebetween, the refrigerating medium being maintained at substantially the same temperature in the several coils, means for supplying a refrigerating medium separately to each individual coil, a separate expansion valve for regulating the refrigerant supply to each coil, and separate thermal control meansattached to refrigerant return conductor of each cooling coil for automatically controlling the correlated individual expansion valve of the refrigerant supply to the coil.

5. An air conditioning unit comprising, a casing, a blower at one end of the casing for discharging air through the casing, a plurality of fins disposed in the casing transversely thereof in the path of the air passing through the casing, a plurality of separated cooling coils supported on the fins and disposed the one ahead of the other in the path-of the air passing through, the refrigerant being maintained at substantially the same temperature in the several coils, a valve connected individually to the inlet of each coil for controlling the supply of refrigerant separately thereto, and means for automatically controlling each refrigerant supply valve according to the load imposed on its individually correlated coil.

6. In an air conditioning unit, a casing, means for passing air to be conditioned through the casing from outside the area to be air conditioned, said casing containing a plurality of separate cooling elements through which air in the casing is passed successively, the refrigerant being maintained at substantially the same temperature in the several cooling elements and said cooling elements operating normally with highest efficiency at a proportionate predetermined capacity for a given degree of temperature of outside air taken into the casing and/or humidity but abnormally below its intended high degree of efficiency when the temperature of the outside air rises appreciably above the given normal.

7. In an air conditioning unit, a casing, means for passing air to be conditioned through the casing from outside thearea to be air conditioned, said casing containing a plurality of separate cooling elements through which air in the casing is passed successively, the refrigerant being maintained at substantially the same temperature in the several cooling elements and said cooling elements operating normally with highest efficiency at a proportionate predetermined capacity for a given degree of temperature of outside air taken into the casing and/or humidity but abnormally below its intended high degree of efficiency when the temperature of the outside air rises appreciably above the given normal,

means for supplying a refrigerant from a common source to each individual cooling element separately, said source including a mulit-speed motor operating at a given speed for normal operating efiiciency of the air conditioning unit, means for controlling the supply of refrigerant from the source individually to each cooling element, thermal control means for each cooling element for automatically controlling the refrigerant supply means of each individual cooling element for normal operation of the air conditioning unit, and separate thermal control means for increasing the speed of said motor to accordingly increase the supply of refrigerant from the source upon an appreciable rise in the temperature of the outside air.

THOMAS W. CARRAWAY. 

